The objective of this contract is to synthesize highly purified, well- characterized compounds that may have utility in the biological processes involved in carcinogenesis. Some of the compounds bay be carcinogens e.g., nitrosamines such as the tobacco specific carcinogens NNN, NNK, or anabasine. Some may be metabolic intermediates e.g., benzo(a)pyrene~ 7,8 diol, which is an intermediate in the metabolic conversion of benzo(a)pyrene to the potent ultimate carcinogen benzo(a)pyrene 7, 8 diol 9,10 epoxide. Some compounds may have demonstrated high mutagenicity and have a known exposure to humans but carcinogenic data are lacking, e.g., fecapentaenes, heterocyclic amine food mutagens. Other compounds may serve as biomarkers of exposure such as PAH DNA or protein adducts.